1. Field of the Invention
The present invention relates to low voltage contactor switches having a three phase contact bank and in particular to such a contactor in which contacting takes place in an evacuated tube.
2. Description of the Prior Art
Low voltage contactors capable of handling voltages of up to 1000 volts for operational switching of motors, capacitors and other electrical devices are well known in the art in which movable contact pieces make and break electrical connections in an air-filled arc chamber. The movable contact pieces of such contactors are generally activated by electromagnetic means. When such contactors are operated within the nominal voltage ranges, deterioration of the contact pieces occurs relatively rapidly due to oxidation caused by the arcing in an oxygen-containing atmosphere so that the contact pieces and arc chambers must be repeatedly replaced over the useful life of the entire contactor. Maintenance of such air gap contactors not only causes increased cost but also results in operational shutdown of the switched devices for the period during such maintenance, which may result in even greater expense.